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On Feb 3, 2016, at 16:13, Warren Young wrote: > A dying hard disk can do it. HDDs try to silently paper over I/O errors, but what they can?t hide is the time it takes to do this. If your HDD is constantly correcting errors at the oxide layer, it will be reeeeeallly sllllow. > > You can try running SMART tests on it, though that?s not guaranteed to show the problem. Well, it?s not ?a? disk: it?s a HW RAID of about dozen (server grade) drives, with a VG/LV on top of that. Are there any log files I can check that test the underlying VG/LV health status? Alfred

I?m running CentOS 6.7 on my build servers, and on one of the servers the builds are taking almost an order of magnitude longer than usual. There are no runaway processes and there is plenty of free memory. So I suspected that file I/O might be slow, and sure enough, that appears to be the case. I ran a simple dd test and compared the results to a ?normal? build server (412 MB/s vs. 31.7 MB/s).

...t be slow, and sure enough, that appears to be the case?.What could cause this A dying hard disk can do it. HDDs try to silently paper over I/O errors, but what they can?t hide is the time it takes to do this. If your HDD is constantly correcting errors at the oxide layer, it will be reeeeeallly sllllow. You can try running SMART tests on it, though that?s not guaranteed to show the problem. Got tested backups? :)

...wrote: > > On Feb 3, 2016, at 16:13, Warren Young wrote: > >> A dying hard disk can do it. HDDs try to silently paper over I/O errors, but what they can?t hide is the time it takes to do this. If your HDD is constantly correcting errors at the oxide layer, it will be reeeeeallly sllllow. >> >> You can try running SMART tests on it, though that?s not guaranteed to show the problem. > > Well, it?s not ?a? disk: it?s a HW RAID of about dozen (server grade) drives smartctl can see through several different types of RAID controller to the underlying physical disks...